add warning about shade minimization

when minimizing output jars, since we use reflection, it is hard to know which classes we use. Either find some way around this or add a warning in README.md

Start by reviewing README.md and the project's reflection usage related to minimizing output JARs. Clarify whether the intended outcome is a workaround or a warning; for the documentation path, done means README.md clearly warns that minimization may omit classes required through reflection.

Written by the indexing model from the issue text.